Method and device of suppressing the deposition of radioactive materials to the constituent components of a nuclear power plant

Purpose: To suppress radiation exposure upon maintenance and inspection in a nuclear power plant by reducing the deposition amount of radioactive materials to the constituent components in contact with coolants. Method: For suppressing the accumulation of radioactive nuclides, it is effective to keep the nuclides from diffusing into the oxide membranes and rendering the oxide membranes so as to easily adsorb cations. For this purpose, the components are constituted with Cr-containing iron materials or those iron materials having Cr membranes or Cr-containing metal membrane formed at the surface in contact with water and the oxide membranes containing more than 12 wt% Cr are formed by treating the surface in contact with water with heated water or steams. Actually, the components previously oxidized by this method are incorporated to the plant, or the method is applied to the pipeways, equipments and the likes of an existent plant by disposing an injection device for the heated water or steam. Thus, the increase in the radiation dose can be suppressed to lower the exposure dose. (Kamimura, M.)